Ten-year incidence of myocardial infarction and prognosis after infarction. Department of Veterans Affairs Cooperative Study of Coronary Artery Bypass Surgery

BACKGROUND. The 10-year incidence of myocardial infarction (fatal and nonfatal) and the prognosis after infarction were evaluated in 686 patients with stable angina who were randomly assigned to medical or surgical treatment in the Veterans Administration Cooperative Study of Coronary Artery Bypass Surgery. METHODS AND RESULTS. Myocardial infarction was defined by either new Q wave findings or clinical symptoms compatible with myocardial infarction accompanied by serum enzyme elevations with or without electrocardiographic findings. Treatment comparisons were made according to original treatment assignment; 35% of the medical cohort had bypass surgery during the 10-year follow-up period. The overall cumulative infarction rate was somewhat higher in patients assigned to surgery (36%) than in medical patients (31%) (p = 0.13) due to perioperative infarctions (13%) and an accelerated infarction rate after the fifth year of follow-up (average, 2.4%/yr in the surgical group versus 1.4%/yr in the medical group). The 10-year cumulative incidence of death or myocardial infarction was also higher in surgical (54%) than in medical (49%) patients (p = 0.20). According to the Cox model, the estimated risk of death after infarction was 59% lower in surgical than in medical patients (p less than 0.0001). The reduction in postinfarction mortality with surgery was most striking in the first month after the event: 99% in the first month (p less than 0.0001) and 49% subsequently (p less than 0.0001). The estimated risk of death in the absence of infarction was nearly identical regardless of treatment (p = 0.75). Exclusion of perioperative infarctions did not alter the findings. CONCLUSIONS. Although surgery does not reduce the incidence of myocardial infarction overall, it does reduce the risk of mortality after infarction, particularly in the first 30 days after the event (fatal infarctions).     

Coronary Artery Surgery Study (CASS): comparability of 10 year survival in randomized and randomizable patients

The Coronary Artery Surgery Study (CASS) includes 780 patients with mild or moderate stable angina pectoris or asymptomatic survivors of a myocardial infarction who were randomized to either medical or surgical therapy and 1,319 patients who were eligible for randomization but were not randomized (randomizable patients). There were no substantial aggregate differences observed in any of the survival comparisons after 10 years of follow-up study between the randomized and randomizable patients assigned to the medical (79% versus 80%) or surgical (82% versus 81%) groups or in patient subgroups stratified according to coronary artery disease extent and left ventricular ejection fraction. Cox regression analyses were done with independent variables known to be predictors of survival, including surgical versus medical therapy and randomized versus randomizable group, to test the null hypothesis of a mortality difference between medical versus surgical assignment according to group assignment (randomized versus randomizable). In no case did the initial group category enter as a significant predictor of survival. The results in the randomizable group reinforce those in the randomized group with respect to the medical versus surgical comparison. Two subgroups are identified with a significant surgical advantage: 1) patients with proximal left anterior descending coronary artery stenosis greater than or equal to 70% and an ejection fraction less than 0.50, and 2) patients with three vessel coronary artery disease and an ejection fraction less than 0.50. In both groups, coronary bypass surgery had a statistically significant beneficial effect on survival (p less than 0.05). After a decade of follow-up, the CASS randomizable patients confirm conclusions reached on the basis of the CASS randomized trial.     

Ten-year follow-up of quality of life in patients randomized to receive medical therapy or coronary artery bypass graft surgery. The Coronary Artery Surgery Study (CASS)

Quality of life indexes were assessed in 780 patients 10 years after randomization to medical therapy (n = 390) or coronary artery bypass graft surgery (n = 390) in the Coronary Artery Surgery Study. At 10 years, mortality was 21.8% in the medical group and 19.2% in the surgical group (p = NS), and 144 (37%) of the medical group had undergone surgery because of increasing chest pain. At study entry, 22% of medical and surgical patients were angina free; at 1 and 5 years after entry, the frequency of asymptomatic patients was 66% and 63% in the surgical group and 30% and 38% in the medical group. However, by 10 years after entry, the proportion of patients free of angina had fallen to 47% in the surgical group and to 42% in the medical group. Activity limitation and use of beta-blockers and long-acting nitrates were less in the surgical than the medical group at 1 and 5 years after entry but little different from the medical group at 10 years after entry. Throughout follow-up, recreational status, employment status, frequency of heart failure, use of other medications, and hospitalization frequency were similar between the two groups. Thus, indexes of quality of life such as angina relief, increased activity, and reduction in use of antianginal medications initially appear superior in patients with stable manifestations of ischemic heart disease assigned to surgery, but by 10 years after entry, these advantages are much less apparent. Although the observed similarities of the medically and surgically assigned groups at 10 years reflect return of symptoms in the surgical group to some extent, a more important explanation is the performance of late surgery in a large proportion of the medically assigned patients, rendering them asymptomatic.     

Features of cardiac arrest episodes with and without acute myocardial infarction in the Coronary Artery Surgery Study (CASS)

Angiographic evidence of coronary artery disease was present in 16,002 patients in the Coronary Artery Surgery Study (CASS) registry. Of these patients, 551 had a history of cardiac arrest before enrollment angiography. Cardiac arrest was a complication of acute myocardial infarction (AMI) in 372 patients (68%). Electrocardiographic documentation of the responsible rhythm was available in 283 patients. Ventricular fibrillation (VF) was present in 112 (60%), ventricular tachycardia (VT) in 41 (22%) and both VT and VF in 26 (14%) patients. Stepwise linear discriminant analysis comparing the 551 cardiac arrest patients with the other 15,451 patients selected left ventricular wall motion score (F = 265), use of digitalis (F = 71), impaired blood supply to any segment (F = 16) and particularly to the anterior wall (F = 11) as discriminating variables associated with cardiac arrest. Patients with cardiac arrest occurring as a complication of AMI were younger (F = 12), had greater impairment of coronary blood supply (F = 7) and were more likely to be on a cholesterol-lowering diet (F = 16) than were patients with arrest remote from infarction. Comparison of patients with VT versus those with VF showed a positive association of VT with age (F = 8), a trend toward worse left ventricular function and presence of a left ventricular aneurysm, but no difference in severity and collateralization of coronary artery disease. It is concluded that cardiac arrest is related to the extent of myocardial damage.(ABSTRACT TRUNCATED AT 250 WORDS)     

冠状动脉分流器在非体外循环冠状动脉搭桥术中的应用

目的对比研究在非体外循环冠状动脉搭桥术中应用冠状动脉分流器的临床效果。方法 86例不停跳冠状动脉搭桥患者分为两组:应用冠状动脉分流器组(实验组,43例)和不应用冠状动脉分流器组(对照组,43例),术后1~3天监测肌酸激酶同工酶(CK-MB)、心肌肌钙蛋白I(c Tn I)、N末端脑利钠肽前体(NT-pro BNP)等指标,并记录并发症发生率、呼吸机使用时间、监护室入住时间及术后住院时间。结果两组病例均痊愈出院。两组人均冠状动脉搭桥支数3~5支,实验组3.6±0.7支,对照组3.6±0.6支,两组没有显著性差异。实验组术后CKMB、cTn I、NT-pro BNP及并发症发生率低于对照组(P0.05),实验组呼吸机使用时间、监护室入住时间及术后住院时间显著缩短(P0.05)。术后1个月、3个月、6个月两组患者左心室射血分数(LVEF)、左心室舒张期末内径(LVEDD)均显著改善,无心绞痛复发。结论在不停跳冠状动脉搭桥术中,应用冠状动脉分流器可以显著减少心肌缺血损伤,对降低围手术期急性心肌梗死发生率、并发症发生率,保护心脏功能,缩短术后恢复时间均有显著临床效果。     

CASS in retrospect: lessons from the randomized cohort and registry. Coronary Artery Surgery Study

The Coronary Artery Surgery Study (CASS) was a prospective, randomized evaluation of the value of coronary artery bypass grafting compared with medical therapy for stable, mildly symptomatic coronary artery disease. Also, the CASS registry collected clinic information and follow-up data from 24,959 nonconsecutive patients undergoing cardiac catheterization from 1974 to 1979. CASS has had a major impact on current management of the coronary disease patient and represents an important contribution to the cardiovascular knowledge base. Despite the large size and valuable contributions of CASS, its findings have been widely misinterpreted, especially regarding indications for coronary artery bypass surgery. This review examines CASS from the viewpoint of its methodology and some of its many published reports. A full understanding of CASS is requisite to avoid clinical misapplication of the findings of this study.     

Early mortality of acute myocardial infarction in patients with and without prior coronary revascularization surgery. A Coronary Artery Surgery Study Registry Study.

BACKGROUND. The Coronary Artery Surgery Study (CASS) Registry is used to evaluate the effect of various baseline clinical and angiographic factors on mortality after acute out-of-hospital myocardial infarction (MI) in patients with and without prior coronary bypass surgery. METHODS AND RESULTS. Among the CASS Registry patients, there were 985 medical and 369 surgical patients who had an MI out of the hospital within 3 years after enrollment. In the medical group, 20% died before hospitalization. Medical patients with baseline three-vessel disease or left ventricular (LV) dysfunction were at high risk of immediate death. For medical patients who were hospitalized with MI, mortality was higher for older patients and those with severe angina as well as for those with extensive disease and LV dysfunction. The total 30-day mortality for medical patients was 36%. In the surgical group, 12% died before hospitalization. Surgical patients with LV dysfunction or prior MI were at highest risk of immediate death. For surgical patients hospitalized with MI, mortality was significantly increased only for patients with baseline LV dysfunction. Mortality was not significantly higher for surgical patients with multivessel disease. The total 30-day mortality for surgical patients was 21%. The prior use of aspirin or beta-blockers was not associated with reduced mortality from subsequent MI for either medical or surgical patients. Although the prevalence of cigarette smoking was high among patients who had an MI, cigarette smoking did not alter the infarct-related mortality rate. CONCLUSIONS. The surgical group had lower mortality rates than the medical group both immediately (p = 0.001), after hospitalization (p less than 0.0001), and at 30 days (p less than 0.0001).     

Ten-year effect of medical and surgical therapy on quality of life: Veterans Administration Cooperative Study of Coronary Artery Surgery

The long-term effect of medical vs surgical therapy on quality of life was evaluated by New York Heart Association functional classification, severity of angina and exercise performance in 427 surviving patients with stable angina at 10 years. Surgically assigned patients had significantly more improvement in functional classification, relief of angina and exercise performance at 1 and 5 years than medically assigned patients. Relative to entry, functional classification was improved in 65% of surgically treated patients at 1 year and in 51% at 5 years, compared with 45% and 40%, respectively, of medically treated patients. Marked improvement in angina was observed in 49% of surgical patients at 1 year and in 41% at 5 years, vs 12% and 17%, respectively, in medical patients. At 10 years, quality of life was not significantly different in the 2 treatment groups: 52% of surgical patients had an improved functional classification, compared with 46% of medical patients, while 33% of surgical and 37% of medical patients had a marked improvement in angina. Exclusion of medical and surgical nonadherers had little effect on the 1- and 5-year comparisons. The 10-year treatment differences, however, were accentuated when 123 medically assigned patients who later underwent operation and who benefited from it were excluded from the analysis. In surgical patients, a strong association was observed between graft patency and functional class at 1 year, but not at 5 and 10 years. In general, patients with some or all grafts open had more improvement in functional classification than patients with all grafts closed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of smoking on survival and morbidity in patients randomized to medical or surgical therapy in the Coronary Artery Surgery Study (CASS): 10-year follow-up. CASS Investigators.

OBJECTIVES. The goal of this study was to ascertain how continued cigarette smoking or smoking cessation related to long-term survival and morbidity in patients with established coronary artery disease managed with medical therapy or coronary bypass surgery. BACKGROUND. Although the association of cigarette smoking with coronary artery disease is well established, the morbidity and mortality associated with smoking behavior in patients with such disease receiving medical or surgical therapy are less well established. METHODS. The 780 patients randomized to medical therapy or coronary bypass surgery in the Coronary Artery Surgery Study (CASS) were subgrouped according to smoking behavior during a mean 11.2-year follow-up interval. Comparisons between smokers and nonsmokers were accomplished by univariate and Cox time-dependent multivariate analyses. RESULTS. Survival at 10 years after entry into the study was 82% among 468 patients who reported no smoking during follow-up (nonsmokers) compared with 77% among the 312 smokers (p = 0.025). Survival was 80% among those who smoked at entry but stopped (quitters) versus 69% among those who continued smoking (p = 0.025). For patients who smoked at baseline and were randomized to bypass surgery, survival at 10 years was 84% among quitters and 68% among nonquitters (p = 0.018); the difference in survival between quitters (75%) and nonquitters (71%) was less among those randomized to medical therapy (p = NS). Among those who smoked at baseline, continued smoking increased the relative risk of death by 1.73. After 10 years, smokers, in comparison with nonsmokers, were less likely to be angina free and more likely to be unemployed and had more activity limitation and more hospital admissions (primarily for chest pain, heart attack, cardiac catheterization, peripheral vascular surgery and stroke). CONCLUSIONS. Thus, among patients with documented coronary artery disease, continued cigarette smoking may result in decreased survival--especially among those undergoing bypass surgery. Moreover, smokers have more angina, more unemployment, a greater limitation of physical activity and more hospital admissions.     

Comparison of the long-term, postsurgical survival of women and men in the Coronary Artery Surgery Study (CASS)

This study compares the survival of men and women an average of 6 years after coronary artery bypass graft surgery (CABG) by means of the Coronary Artery Surgery Study (CASS) registry. Subjects included in these analyses were the 6100 men and 1097 women who survived surgery. Medical history and physical and laboratory information were collected from each patient at baseline. Men and women were compared for differences in baseline characteristics, long-term survival (by means of the Cox proportional hazards models), and predictors of long-term survival. In this study women, at baseline, were older and more likely to have hypertension and diabetes compared to men; whereas men were more likely to have had prior coronary heart disease. In this study of CASS participants there was no difference between men and women with regard to survival after CABG. There was also no difference between men and women in predictors of 6-year mortality. Two baseline variables were strongly related to subsequent mortality in both men and women: a high left ventricular wall motion score and taking both digitalis and diuretics (for women: relative risk = 2.31, confidence interval = 1.38 to 3.87; for men: relative risk = 1.90, confidence interval = 1.45 to 2.50).     

Ten-year outcome after coronary angioplasty in patients with single-vessel coronary artery disease and comparison with the results of the Coronary Artery Surgery Study (CASS)

The 10-year results of randomized trials comparing percutaneous transluminal coronary angioplasty (PTCA) in patients with single-vessel coronary artery disease (CAD) with coronary artery bypass grafting (CABG) and medical treatment are not available yet. The aim of this evaluation was to compare our 10-year follow-up results after PTCA in patients with single-vessel CAD with the 10-year follow-up results after CABG and medical treatment in the Coronary Artery Surgery Study (CASS) trial. We evaluated the clinical outcome of 509 patients with single-vessel CAD 10 years after coronary angioplasty. The data were compared with the results of 214 patients with single-vessel CAD after CABG or medical treatment from the CASS trial. End points were defined as death and myocardial infarction. Statistical evaluation was performed by life-table analysis and 2-sided Fisher's exact test. The rate of survival was 86% 10 years after PTCA compared with 85% after CABG and 82% after medical treatment in patients from the CASS trial (p = NS). Survival free from myocardial infarction was 77% after coronary angioplasty, 70% after CABG, and 72% after medical treatment (p = NS). Thus, in patients with single-vessel CAD, infarct-free survival 10 years after coronary angioplasty compared favorably with the results after bypass surgery or medical treatment from the CASS trial.     

Coronary thrombolysis by intravenous streptokinase in acute myocardial infarction: Acute and follow-up studies

Coronary arteriography was performed before, immediately after, and 9 to 14 days after administering i.v. Streptokinase (850,000 to 1,500,000 IU) to 43 patients within 6 hours of myocardial infarction. Ventricular function was determined by contrast ventriculography before and 9 to 14 days later and by radionuclide studies at clinical follow-up 8 months later. Early reperfusion occurred in 49% of patients, but in only 35 % was it sustained. In patients with sustained reperfusion, early ventricular dysfunction was significantly reduced 9 to 14 days and 10 months later, and frequency of infarction, sudden death, and angina pectoris was not increased at follow-up. No serious bleeding occurred.     

Coronary lesions in myocardial infarction

The authors analyse the coronary lesions in 285 patients with primary myocardial infarction (164 anterior, 121 inferior infarcts) undergoing coronary angiography an average of 4 months after infarction. The statistical study of the analytical table of the lesions according to severity and site, demonstrated a significant difference in each group (p less than 0,001): --there was a very clear dominance of occlusion of the LAD artery in anterior infarction but severe narrowing (greater than or equal to 70%) was observed mainly on the right coronary and left circumflex arteries; --in inferior infarction, the incidence of occlusion was higher on the right coronary artery and severe narrowing was divided between the LAD and left circumflex arteries. Controlateral, double or triple vessel disease was present in 74% of anterior and 85% of inferior infarcts. There were many more patients with double and triple vessel lesions than with single vessel disease. Residual angina gave no indication of the extension of the lesions in anterior infarction but patients with this complication after inferior infarction had a higher rate of triple vessel disease. Stress testing is exploitable in inferior infarction but did not give any discriminating results. In this series, angina and stress testing only allowed triple vessel disease to be suspected in patients with inferior infarction. A coronary arteriographic study, by showing the severity and controlateral extension of the lesions, comparable in primary anterior and inferior infarction, gives important prognostic information and allows assessment of surgical possibilities.     

Risk of developing an acute myocardial infarction or sudden coronary death in patients with exercise-induced silent myocardial ischemia. A report from the Coronary Artery Surgery Study (CASS) registry

To evaluate whether patients with silent myocardial ischemia during exercise testing are at increased risk for developing a subsequent acute myocardial infarction or sudden death, the data on 424 such patients with proven coronary artery disease (CAD) from the Coronary Artery Surgery Study (CASS) registry were analyzed. These patients (group 1) were compared with 456 other patients with CAD (group 2) who had both ischemic ST depression and angina pectoris during exercise testing and with 1,019 control patients without CAD. The probability of remaining free of a subsequent acute myocardial infarction or sudden death at 7 years was 80 and 91%, respectively, for group 1, 82 and 93%, respectively, for group 2 (difference not significant, compared with group 1), and 98 and 99%, respectively, for the control patients (p less than 0.001), compared with group 1 or 2). Among patients in group 1, the probability of remaining free of myocardial infarction and sudden death at 7 years was related to the severity of CAD and presence of left ventricular (LV) dysfunction, and ranged from 90% for patients with 1-vessel CAD and preserved LV function to 38% for patients with 3-vessel CAD and abnormal LV function (p less than 0.001). Thus, patients with either silent or symptomatic ischemia during exercise testing have a similar risk of developing an acute myocardial infarction or sudden death--except in the 3-vessel CAD subgroup, where the risk is greater in silent ischemia. The risk of patients with silent myocardial ischemia is based primarily on angiographic variables.